The far-infrared–radio correlation (FRC) is one of the most promising empirical constraints on the role of cosmic rays (CRs) and magnetic fields in galaxy formation and evolution. While many theories have been proposed in order to explain the emergence and maintenance of the FRC across a gamut of galaxy properties and redshift, the nonlinear physics at play remain unexplored in full complexity and within a cosmological context. We present the first reproduction of the z ∼ 0 FRC using detailed synthetic observations of state-of-the-art cosmological zoom-in simulations from the Feedback in Realistic Environments (FIRE-3) suite with explicitly evolved CR proton and electron (CRe) spectra, for three models for CR transport and multichannel active galactic nucleus (AGN) feedback. In doing so, we generally verify the predictions of "calorimeter" theories at high FIR luminosities (L60 μm ≳ 109.5 L⊙) and at low FIR luminosities (L60 μm ≲ 109.5 L⊙), the so-called "conspiracy" of increasing UV radiation escape in tandem with increasing CRe escape, and find that the global FRC is insensitive to orders-of-magnitude locally variable CR transport coefficients. Importantly, the indirect effect of AGN feedback on emergent observables highlights novel interpretations of outliers in the FRC. In particular, we find that in many cases "radio-excess" objects can be better understood as "IR-dim" objects with longer-lived radio contributions at low z from Type Ia supernovae and intermittent black hole accretion in quenching galaxies, though this is sensitive to the interplay of CR transport and AGN feedback physics. This creates characteristic evolutionary tracks leading to the z = 0 FRC, which shape the subsequent late-time behavior of each model.
Hooks, Lines, and Sinkers: How Active Galactic Nucleus Feedback and Cosmic-Ray Transport Shape the Far-infrared–Radio Correlation of Galaxies
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1.
California Institute of Technology
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2.
University of Edinburgh
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3.
Columbia University
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4.
Kavli Institute for Particle Astrophysics and Cosmology
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5.
Wesleyan University
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6.
Carnegie Observatories
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University of California, San Diego
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8.
Eureka Scientific
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Kavli Institute for the Physics and Mathematics of the Universe
- 10. Flatiron institute
Abstract
Acknowledgement
© 2025. The Author(s). Published by the American Astronomical Society.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Copyright and License
We wish to recognize and acknowledge the past and present Gabrielino-Tongva people and their unceded Indigenous lands upon which this research was conducted. Support for S.P. and P.F.H. was provided by NSF Research Grants 20009234 and 2108318, NASA grant No. 80NSSC18K0562, and a Simons Investigator Award. Numerical calculations were run on NSF/TACC allocations AST21010, TG-AST140023, and TG-PHY240164, and NASA HEC SMD-16-7592. R.K.C. was funded by support for program #02321, provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. R.K.C. is grateful for support from the Leverhulme Trust via a Leverhulme Early Career Fellowship. I.S.B. was supported by NASA through a Hubble Fellowship, grant No. HST-HF2-51525.001-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS 5-26555. S.W. received support from the NASA RIA grant No. 80NSSC24K0838. D.K. was supported by NSF grant AST-2108324. The Flatiron institute is supported by the Simons Foundation.
Facilities
National Science Foundation (NSF) eXtreme Science and Engineering Discovery Environment (XSEDE) computational services - .
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Additional details
- Alternative title
- Hooks, Lines, and Sinkers: How AGN Feedback and Cosmic-Ray Transport shape the Far Infrared-Radio Correlation of Galaxies
- National Science Foundation
- 20009234
- National Science Foundation
- AST-2108318
- National Aeronautics and Space Administration
- 80NSSC18K0562
- National Science Foundation
- AST21010
- National Science Foundation
- TG-AST140023
- National Science Foundation
- TG-PHY240164
- National Aeronautics and Space Administration
- SMD-16-7592
- Space Telescope Science Institute
- National Aeronautics and Space Administration
- NAS 5-03127
- Leverhulme Trust
- National Aeronautics and Space Administration
- HST-HF2-51525.001-A
- National Aeronautics and Space Administration
- NAS 5-26555
- National Aeronautics and Space Administration
- 80NSSC24K0838
- National Science Foundation
- AST-2108324
- Simons Foundation
- National Aeronautics and Space Administration
- NASA Hubble Fellowship -
- Accepted
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2024-12-20Accepted
- Available
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2025-02-07Published
- Caltech groups
- Astronomy Department, TAPIR
- Publication Status
- Published